* Tweak the accessibility/reduced motion text
include mention of carousel slides, remove the (now inaccurate, as Firefox 63 includes it too) mention that support is limited to Safari/macOS
xref https://github.com/twbs/bootstrap/issues/27525
* Add new callout for reduced motion
* Add variable to control prefers-reduced-motion media query support
* Add callout about prefers-reduced-motion to all components currently using animation which are affected
